Drying cylinder



Feb. 11, 1969 e. OVERTON 3,426,839

DRYING CYLINDER Filed Dec. 5, 1966 IN VENTOR. 64 0 1/5270 A TTORNE YSUnited States Patent 3,426,839 DRYING CYLINDER Glen Overton, Allegan,Mich. 49010 Continuation-impart of application Ser. No. 559,693,

June 22, 1966, which is a continuation of application Ser. No. 375,035,June 15. 1964, now abandoned. This application Dec. 5, 1966, Ser. No.599,060 The portion of the term of the patent subsequent to Mar. 14,1984, has been disclaimed U.S. Cl.165--89 7 Claims Int. Cl. F28f 02;F26b 11/02; F28d 7/00 ABSTRACT OF THE DISCLOSURE A dryer drum or dryingcylinder heated eificiently and uniformly with internal steam jetsclosely adjacent the inside surface of the cylinder wall and fed withmore steam than can be completely condensed in the cylinder to providejet streams which mechanically scour the inner surface of the cylinderWall to break up and remove condensate filnr thereby increasing the heattransfer through the cylinder wall and lessening the amount ofcondensate to be removed. Uncondensed steam i discharged from thecylinder for use elsewhere. The steam jets are provided bylongitudinally extending pipes inside the cylinder closely adjacent thecylinder wall and carried by spoke pipes radiating from a central pipeor axle of the cylinder to revolve with the cylinder. The live steam isfed into this central axle or pipe through one end of the cylinder andexited at the other end of the cylinder. Pressure regulators maintain adesired differential steam pressure drop between the inlet and outletends of the cylinder.

RELATED APPLICATIONS This application is a continuation-in-part of mycopending application Ser. No. 559,693 entitled, Drying Cylinder, filedJune 22, 1966, now Patent No. 3,308,554 granted Mar. 14, 1967 whichapplication in turn is a full continuation of my application Ser. No.375,035 filed June 15, 1964 and now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionpertains to the art of heating rotating drying cylinders or dryer drumswith condensable fluids such as live steam and particularly to the artof using steam jets to scour the surface being heated for breaking upany condensate film on the surface to increase the heat transfer throughthe surface.

Description of the prior art In my aforesaid applications Ser. Nos.559,693 and 375,035 the illustrated drying cylinders are equipped Withstationary internal steam jet heating apparatus and steam is preferablyfed into both ends of the cylinder with one end supplying the jets andthe other end supplying the central interior of the drum with livesteam. In some installations, however, the drying cylinder has a centralpipe or axle extending therethrough in fixed relation to the end headsof the cylinder and of course this pipe or axle revolves with thecylinder. The present invention solves the problem of steam jet heatingof such cylinders by using the central pipe or axle as a steam conduit,allowing the jet apparatus to rotate with the cylinder and lessening thecondensate removal problem by exiting uncondensed steam from thecylinder for further use elsewhere.

3,426,839 Patented Feb. 11, 1969 SUMMARY The gist of the invention is topass more steam through a drying cylinder than can :be condensed in thecylinder and to use this surplus steam as a mechanical scouring media tobreak up moisture films which might build up on the cylinder wall. Thesteam is released into the cylinder closely adjacent the cylinder wallin the form of a myriad of high pressure steam jets directednon-radially against the cylinder wall to scour the surface thereof freefrom condensate and to prevent formation of localized hot spots on thecylinder. The steam jets release the steam at angles of about 45 fromthe radius of the cylinder so that the jet streams will impinge againstthe cylinder wall at high velocity having both radial andcircumferential force components thus providing a good scrubbing actionon the cylinder wall. Each jet pipe may have two rows of jet openings sothat the jet sprays will extend in nonradial directions on both sides ofthe pipe and have downward circumferential components to direct anycondensate or moisture film to the bottom of the cylinder.

The jet pipes also have jet outlets at the ends thereof to direct jetstreams against the very end edges of the cylinder for insuring completeheating of the entire length of the cylinder.

The central axle or pipe in the cylinder is preferably plugged near oneend thereof to divide the interior of the axle into an elongated steammanifold for feeding the jet pipes and into a short exiting manifold forreleasing the surplus steam from the cylinder. This short manifold canalso receive the condensate pipe therethrough for removing the condensedsteam from the bottom of the cylinder.

It is then an object of this invention to provide a dryer with steamjets closely adjacent the drying wall for inrpinging live steamnon-radially against the wall to scour condensate films off of the walland to lessen condensate rem-oval requirements by maintaining a steampressure differential in the drum and exiting surplus steam for useelsewhere.

Another object of the invention is to provide a steam jet heater fordrying cylinders equipped with central axles wherein the steam jet meansare supported from the axles and rotate with the cylinders.

Another object of this invention is to provide a steam jet heatingapparatus for drying drums which maintain a differential steam pressurein the drum to lessen condensate removal requirements.

A further and specific object of this invention is to provide a dryingcylinder especially siutable for drying foodstuff such as milk, slurriesand the like at high speeds and without local overheating wherein theheat is sup plied from live steam jets and the heating surface isscoured free from condensate films by the jets and the condensate iskept to a minimum by existing surplus steam.

Other and further objects will be apparent to those skilled in this artfrom the disclosures in the aforesaid applications and the hereinafterspecific disclosures of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a somewhat diagrammaticlongitudinal cross-sectional view, with parts in elevation, of a dryingcylinder equipped with jet heating apparatus according to thisinvention;

FIGURE 2 is a transverse cross-sectional view taken along the line 11-11of FIGURE 1;

FIGURE 3 is a transverse cross-sectional view similar to FIGURE 2 butshowing added jet pipes; and

FIGURE 4 is an enlarged fragmentary cross-sectional view taken along theline IV 1V of FIGURE 1.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS The drying cylinder ofFIGURES 1 and 2 has a cylindrical metal shell 11 with inturned endflanges 12, 12 and end heads 13, 13 secured to the flanges and providedwith hollow journals 14 to rotatably support the cylinder. The end headsare connected by a central axle or reinforcing tubular pipe 15 extendingthrough the central interior of the shell 11 and cooperating with thehollow interiors of the journals 14 to provide a central passageway 16through the cylinder. A plug 17 is secured in this passageway 16 nearone end head 13 and the axle or tube 15 is provided with ports 18between the plug and this adjacent end head for joining the interior ofthe tube or axle with the interior of the cylinder.

The plug 17 divides the passageway 16 into an elongated steam inletmanifold 19 on one side of the plug 17 and a steam outlet manifold 20 onthe opposite side of the plug 19.

The axle or tube 15 has central radial spoke pipes 21 extending from themidway thereof. Additional spoke pipes 22 extend radially from the axleor tube 15 adjacent the ends of the axle or tube. All of these spokepipes communicate with the passage 19 provided by the axle or tube.These spoke pipes carry T fittings 23 at their outer ends which arepositioned closely adjacent the inner surface of the cylinder 11. TheseT fittings support longitudinal jet pipes 24 which extend closelyadjacent the cylinder wall from one end flange 12 to the other. The jetpipes may be sectioned to have screw thread connection with the Ts 23but for descriptive purposes may be considered as single units extendinglongitudinally along the entire length of the drying cylinder.

In the form of the invention illustrated in FIGURES 1 and 2 four jetpipes 24 are provided in equally spaced relation in the drying cylinderand each of these four spray pipes is supported by the sets of centralspoke pipes 21 and end spoke pipes 22. It will be understood howeverthat any number of spoke pipes may be used depending on the length ofthe drying cylinder. For stability and equal steam distribution alongthe entire length of the jet pipe, it is preferred that at least twospoke pipes be used for each jet pipe and that they be located at ornear the ends of the spoke pipe.

Each jet pipe 24 has two rows of jet openings or apertures 25 at closelyspaced relation along the length thereof. These jet openings 25 as bestshown in FIG- URE 4 are positioned to direct jet sprays 26 on each sideof the radius R for the cylinder 11. As illustrated the jet streams 26on one side of the radius R are at an angle A while the jet streams onthe other side are at an angle B. These angles may be the same ordifferent and are about 45 so that the jet streams 26 will impinge onthe shell wall in non-radial directions but will have force componentsimpacting the wall both radially and circumferentially to provide a goodscrubbing action for breaking up the film of moisture on the wall.

The ends of the spray pipes 24 also have jet outlets 27 to eject jetsprays 28 toward the very ends of the shell 11. The end flanges 12 ofthe shell may be peripherally grooved at 29 to receive these sprays 28for heating the shell up to the very ends thereof.

A steam inlet supply pipe 30 at the left-hand end of the cylinder inFIGURE 1 supplies live steam to the through passage 16 where the plug 17confines it to the passageway portion 19. This inlet 30 has a shut-offvalve 31, a pressure regulator valve 32 downstream from the shut-offvalve, a control 33 for the regulator 32, an indicator gauge 34 for thepressure regulator and blow-off valves 35 and 36 on the upstream anddownstream sides respectively of the pressure regulator. A rotary steamjoint 37 connects the steam inlet with the hollow journal 14 of theadjacent 9 1d head 13 and steam at the desired pressure under thecontrol of the regulator 32 as set by the control 33 is thus fed intothe passageway portion 19 for flow through the spoke pipes 21 and 22 tothe four jet pipes 24 and thence through the orifices 25 thereof to formthe jet streams 26 and 28.

A condensate removal siphon tube 38 is carried by the central axle orpipe 15 beyond the plug 17 and extends through the passage 20. Thesiphon tube 38 is closely adjacent the end head and has an inlet end 39closely adjacent the shell 11 positioned to scoop up condenate water onthe ascending side of the shell 11 as best shown in FIGURE 2. The siphontube 38 extends through the journal 14 and into a rotary steam joint 40.

Surplus steam and water removal apparatus is provided at the right-handend of the cylinder 10 and includes a fitting 41 on the journal 40receiving condensate from the outlet end 42 of the siphon tube 38 andalso receiving surplus steam from the passageway 20. The condensatewater is drained through a pipe 43 to a trap. The surplus steam isreceived by a steam outlet pipe 44 with a back pressure regulating valve45 the pressure of which is controlled by a regulator 46 as indicated byan indicator -47. Shut-off valves 48 and 49 are provided respectively onthe upstream and downstream sides of the regulator valve 45. A reliefvalve 50 is provided in the steam outlet line 44 on the upstream side ofthe regulator 45.

The end heads 13 for the shell 11 have access holes 51 therein caused bycovers 52 when the apparatus is in operation.

-In the embodiment shown in FIGURE 3 the drying cylinder 10 is equippedwith twice the number of jet pipes as is shown in FIGURE 2. In thisarrangement the eight jet pipes 24 are spaced equally around theinterior of the shell 11 and are each supported by the central spokepipes 21 and the end spoke pipes 22. From this it will be understoodthat any desired number of jet pipes can be used to meet conditions.

OPERATION OF THE DEVICE The drying cylinder 10 may be used alone or incombination with identical cylinders to provide single or twin drumdrying apparatus. The material to be dried is fed to the periphery ofthe shell 11 and the dried film is scraped from this periphery as isconventional. The capacity of the dryer of course depends on the speedof removal of the liquid content of the material being dried withoutdamaging the end product. The device of this invention by efiicientlyand uniformly heating the shell 11 .has materially speeded up the dryingoperation of drum dryers and dryers equipped with the heating apparatusof this invention have increased production as much as onethird withoutincreasing the cylinder sizes.

In operating the device of this invention steam at a selectedpredetermined pressure, preferably in the range of to lbs. per squareinch is fed from the inlet 30 into the passageway portion .19 where itis distributed by the spoke pipes 21 and 22 to the jet pipes 24. Thesespoke pipes are positioned so that each jet stream 26 emerging from thejet pipes 24 will have the same velocity and will impinge on the dryershell as shown in FIGURE 4 with force components both radially andcircumferentially to efliciently scour the shell and remove moisturefilm therefrom. The dryer 10 and the heating apparatus in the dryer allrotate together in a clockwise direction as indicated in FIGURE 2 andWhile the jet streams 26 thus are in fixed relation to the shell 12 theynevertheless span a sufficient area of the shell so as to coact with thestreams from the next adjacent spray pipes in a manner to equally heatthe entire circumference of the shell.

The steam outlet apparatus is regulated so that a deseired steampressure is maintained in the drum. The jets supply suificient steam tomaintain the set back pressure. Outlet pressures of from 60 to 100 lbs.per square inch are preferred when the inlet pressure is from 100 to 140lbs. per square inch. Thus differential steam pressures of about 45 lbs.per square inch are maintained, although it should be understood thatthe regulating valves 32 and 45 can be controlled to maintain anydesired steam pressure in the drum.

The surplus steam in the drum flows through the ports 18 into thepassageway 20 and thence to the steam outlet 44,

Some condensate is desired to obtain the latent heat of the condensationof steam for transfer through the shell 11 and this condensate isremoved by the siphon tube 38.

It will therefore be understood that the heating of the shell 11 isobtained by differential steam pressure which is maintained in the drumand also by the latent heat released in the condensation of some of thesteam. It will also be understood that the steam jets scour the walls ofthe shell 11 to at least partly remove the condensate film thereon andthereby greatly enhance the heat transfer through the shell to thematerial being dried on the shell. It will also be understood that theheating apparatus of this invention revolves with the drum and iscarried by the axle or central pipe of the drum.

It will be understood that variations and modifications may be effectedwithout departing from the spirit and scope of the novel concepts ofthis invention.

I claim:

-1. A drying apparatus which comprises a cylindrical shell, end headsclosing the ends of the shell, journals on the end heads for rotatablysupporting the shell, a central pipe extending axially through saidshell and attached to said end heads, a plug in said pipe adjacent oneend head dividing the interior of the pipe into an elongated steam inletpassage and a short steam outlet passage, ports in said pipe joining theinterior of said shell with said outlet passage, a siphon tube extendingthrough said steam outlet passage and having an inlet end for removingcondensate from the shell, spoke pipes radiating from said central pipecommunicating with the steam inlet passage, jet pipes carried by theouter ends of the spoke pipes closely adjacent the shell and extendingalong the full length of the shell, said jet pipes having outletapertures positioned to direct steam jets in non-radial directions forscrubbing and heating the shell wall, means for introducing steam undercontrolled pressure into the steam inlet passage for discharge throughthe spoke pipes and jet pipes, means for removing steam from the steamoutlet passage, means for maintaining the steam outlet pressure at apredetermined differential relative to the steam inlet pressure, andmeans for separating the condensate from the exiting steam.

2. A drying apparatus which comprises a rotatable horizontal dryer drumhaving a cylindrical shell, end heads closing the ends of the shell andhollow journals projecting from the end heads for rotatably supportingthe drum, a central pipe fixed to the end heads and extending throughthe drum in full communication with the hollow journals, a steam inletconnected to one of said hollow journals, a steam outlet connected tothe other of said hollow journals, means dividing said pipe into anelongated passage communicating with the steam inlet and a shortpassageway communicating with the steam outlet, spoke pipes radiatingfrom the central pipe communicating with the inlet passage, longitudinaljet pipes carried by the outer ends of the spoke pipes closely adjacentthe cylinder wall, said jet pipes having jet outlets along the lengthsthereof positioned to direct steam jets in non-radial directions againstthe cylinder wall, a condensate siphon tube depending from the centralpipe and extending through the outlet passage portion thereof, saidsteam inlet supplying live steam to the inlet passage at a predeterminedpressure, said steam outlet maintaining a desired back pressure in thesteam outlet portion of the pipe and means for separating condensatefrom surplus steam in the steam outlet.

3. A dryer drum which comprises a cylindrical shell, end heads closingthe ends of the shell, hollow journals projecting from the end heads, ahollow axle for said drum secured at its ends to said end heads andcooperating with said hollow journals to provide a through passage inthe center of the drum, a plug in said axle dividing said throughpassage into a steam inlet portion and a steam outlet portion, saidsteam outlet portion having ports communicating with the interior of thedrum, means for feeding live steam into the steam inlet portion of theaxle, spoke pipes carried by the axle and radiating therefrom forreceiving steam from the steam inlet portion thereof, longitudinal jetpipes carried by the outer ends of the spoke pipes for ejecting thesteam in nonradial directions against the interior of the shell, steamoutlet control means communicating with the steam outlet portion of saidaxle to maintain a desired steam back pressure in the drum, and acondensate removal tube extending through one of said journals forremoving condensate from the interior of the drum whereby the shell isheated with live steam, surplus steam is removed from the drum, andcondensate water is removed from the drum.

4. Heating apparatus for a drum dryer having a hollow central axleextending therethrough which comprises spoke pipes radiating from saidaxle for receiving live steam therefrom, jet pipes carried by the outerends of the spoke pipes closely adjacent the drum, means for feedinglive steam into one end of the axle, means for removing excess steamfrom the other end of the axle, and steam control means for maintaininga live steam pressure differential between the steam inlet portion ofthe axle and the steam outlet portion of the axle.

5. The drying apparatus of claim 1 wherein from four to eight jet pipesare provided in the shell.

6. The drying apparatus of claim 1 wherein each jet pipe has a centralspoke pipe and two end spoke pipes.

7. The drying apparatus of claim 1 wherein each jet pipe has two spacedrows of outlet apertures along the length thereof positioned fordischarging jet sprays at angles of about 45 relative to the radius ofthe shell.

References Cited UNITED STATES PATENTS 1,189,761 7/1916 White 34-1241,768,777 7/1930 Muller 34-124 2,599,346 6/1952 Oflen -89 2,885,7905/1959 Cram 165-89 X 2,772,075 11/ 1956 Mayer 165-89 3,308,554 3/1967Overton 34-124 ROBERT A. OLEARY, Primary Examiner. THEOPHIL W. STREULE,Assistant Examiner.

US. Cl. X.R. 34-124

